Due to advantages such as low cost and suitability for mass production, transfer molding is widely used as a method of packaging semiconductor devices, such as integrated circuits (ICs) and large scale integration (LSI) chips, with epoxy resin compositions. In transfer molding, modification of epoxy resins or phenol resins as curing agents can lead to improvements in the characteristics and reliability of semiconductor devices. Such epoxy resin compositions include an epoxy resin, a curing agent, a curing catalyst, and the like.
Although imidazole catalysts and amine catalysts have generally been utilized as the curing catalyst, these catalysts exhibit a curing acceleration effect at low temperature. For example, when an epoxy resin is mixed with other components before curing, the epoxy resin composition is partially cured by heat generated from the mixture system or externally applied heat, and, after completion of mixing, the epoxy resin composition can be further cured during storage at room temperature. Such partial curing can cause the epoxy resin composition to exhibit reduction in viscosity and deterioration in fluidity. In addition, since such state change is not uniform within the epoxy resin composition, the composition is subject to local curing variation. This can cause deterioration in mechanical, electrical and chemical properties of a molded article in manufacture of the molded article from the thermosetting epoxy resin composition through curing at high temperature. Accordingly, since use of the curing accelerator requires precise control of mixing time of each component and strict management of storage at low temperature, transportation, and molding conditions, the epoxy resin composition becomes difficult to handle. Further, if the composition is curable at a wide temperature range, this can cause deterioration in productivity and processability.
In the related art, Korean Patent Publication No. 10-0290448 discloses an epoxy resin curing catalyst which is a carboxylate of a bicyclic amidine.